Environmental studies of the genus Rosa.

  • Morteza Khosh-Khui

Student thesis: Doctoral ThesisPhD


Experiments were conducted to investigate the effects of intensity, duration, quality and timing of light on the glasshouse rose (Rosa hybrida L. cv. Baccara). Effects of treatments were studied on flower yield, quality and index; blind shoots; abnormal flowers; days to flowering; stems remaining on the plants; stem length; node number; average internode length; neck node length; leaves and leaflets number; stem diameter; terminal leaflet area; petal size; petal number; fresh and dry weight. Data presented, indicated that production of Baccara in South West England followed solar energy curve; the highest yield obtained after receiving the most natural light in vegetative growth phase. Lighting increased flower yields and decreased blind shoots, especially in limited natural light periods of the year, proportionately to the quantity of light received by the plants; intensity being more effective than duration. Bottom breaks and axillary shoots developments were stimulated Dy lighting; the latter was more responsible for higlier yields. Lighting promoted earlier flowering mostly proportional to light intensity. Night break with high pressure mercury lamps increased flower yield significantly and decreased the days to flower non significantly. Cyclic lighting with low light intensity of incandescent lamps did not affect the roses. Overall results suggested that Baccara rose might be classified as a day neutral plant under the condition of this investigation. High pressure sodium lamps proved to be an efficient light source for rose supplementary lighting. Supplementary lighting was more effective when it was provided in vegetative than reproductive growth phase. Generally all the recorded characters improved under light but on average the differences were non significant. However, node number remained almost unchanged and neck node was shorter under higher light intensity and duration. Significant correlation coefficients were demonstrated between some characters of cut stems which were independent of stem nature, seasons and light treatments.
Date of Award1975
Original languageEnglish
Awarding Institution
  • University of Bath

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